Large cranes, in particular large crawler cranes, require a considerable counterweight which counteracts the lifted payload and prevents tilting of the crane. This counterweight can be applied by a central ballast, an uppercarriage ballast or also by a ballast on the derrick boom. An example derrick ballast includes a ballast plate supported with respect to the ground via corresponding implements for receiving the ballast. As an alternative, a completely suspended ballast or also a derrick ballast carried by a ballast wagon is possible.
Against this background special ballast wagons have been developed, which are designed as independently driven vehicles and therefore are traversable together with the crane, in order to ensure a largely unrestricted crane operation. Such a solution is known for example from EP 1 934 129 B1, in which beside a corresponding ballast wagon, an additional counterweight in the form of a suspended ballast also is provided. As on slewing or traversing of the crane, the counterweight also should be moved, it is proposed in the reference that the non-traversable counterweight is activatable before the traversable counterweight, i.e., the counterweight lifts off before the ballast wagon. Such solutions, however, always require a complex in-house development of an appropriate ballast wagon which exclusively is used for ballasting. Furthermore, such ballast wagon must separately be transported to the construction site for use of the crane, which has a disadvantageous effect on the operating costs incurred, since the same generally depend on the required ballast mass.
A further issue for the dimensioning of the required ballast arises during the erection of long boom combinations. The boom lying on the ground has a comparatively large lever arm and therefore induces a relatively large load moment, which by far exceeds the load moments occurring later on during the crane operation. As workaround for this problem, DE 203 14 503 U1 therefore proposes to arrange the auxiliary crane required for the set-up operation of the crane as an additional ballast on the uppercarriage of the crane, in order to be able to compensate the load moments occurring during the erecting operation.
From DE 10 2012 002 040 a similar solution is known, in which additional ballast elements can be mounted on the auxiliary crane, when the weight of the auxiliary crane is not sufficient as ballast. The additional ballast elements are attached to the crawler tracks of the auxiliary crane.
During the erection of very long booms, in which a larger counterweight is required, especially for the erecting operation, the known solutions were found to be insufficient. However, this high counterweight only is required for erecting these very long booms. After erection, the long boom is operated in a steep position and comparatively only little counterweight is required. This comparatively low counterweight in crane operation can be provided wholly or at least in part by the uppercarriage ballast. In addition, an additional ballast may be necessary.
Therefore, it is the object of the present disclosure to provide an example method for operating a crane, in which for erecting very long booms, a sufficiently high counterweight easily can be provided, when necessary.
This object is solved by a method for operating a crane with a traversable undercarriage, an uppercarriage rotatably mounted on the same with luffing main boom and derrick boom arranged thereon, wherein an auxiliary crane with telescopic boom as derrick ballast is connected with the crane and via the telescopic boom of the auxiliary crane the derrick ballast radius is adjusted. Therein, for erecting the main boom, a suspended ballast is lifted in addition to the auxiliary crane provided as derrick ballast, wherein first the auxiliary crane is lifted, before the suspended ballast is lifted, when necessary.
An example crane according to the present disclosure for carrying out the method discussed above may include a traversable undercarriage, an uppercarriage rotatably mounted on the same with luffing main boom and derrick boom arranged thereon and with a crane controller, characterized in that as derrick ballast it includes an auxiliary crane and in addition a suspended ballast, which via guying means both are connected with a crossbeam which in turn is connected with the derrick boom via guy rods. Additionally or optionally, between the derrick boom and the crossbeam, a variable-length element each in the form of a hydraulic cylinder may be provided. Additionally or optionally, on the undercarriage of the auxiliary crane, receptacles for receiving the slings may be arranged on the undercarriage such that they are located closer to the crane than the overall center of gravity of the auxiliary crane, wherein the receptacles advantageously are demountable or each laterally extendable from the undercarriage.
The present disclosure relates to a method for operating a crane with a traversable undercarriage, an uppercarriage rotatably mounted on the same with luffing main boom and derrick boom arranged thereon, wherein an auxiliary crane with telescopic boom as derrick ballast is connected with the crane and via the telescopic boom of the auxiliary crane the derrick ballast radius is adjusted. According to the present disclosure, a suspended ballast is lifted in addition to the auxiliary crane provided as derrick ballast for erecting the main boom, wherein first the auxiliary crane is lifted, before the suspended ballast is lifted, when necessary.
Thus, an auxiliary crane with telescopic boom as derrick ballast is connected with the crane. The ballasting possibility for example can be employed during the regular use of the crane or already during the crane set-up operation, especially during the erecting operation of the crane main boom. Via the telescopable length of the telescopic boom, the radius of the ballast can be adjusted.
As auxiliary crane, a comparatively small crane can be used, which for example is required for the set-up operation of the crane according to the present disclosure. What is useful in particular is an auxiliary crane designed as mobile or also as crawler crane.
As compared to a conventional derrick ballast, the auxiliary crane utilized as derrick ballast has the advantage that it can independently travel on the construction site, wherein the required repositioning times of the entire crane system from one site of use to the next site of use on the construction site can be reduced considerably.
During erection of the very long booms, the auxiliary crane first is lifted from the ground as ballast, when necessary. If this ballast is not sufficient, the further suspended ballast provided according to the present disclosure additionally is lifted.
Between the derrick boom and the auxiliary crane, at least one guying advantageously can be arranged such that, from the derrick boom, guy rods are guided to a crossbeam, on which on the one hand guying means for bracing the auxiliary crane and on the other hand guying means for connection with the suspended ballast are arranged.
Advantageously, the guying means for bracing the auxiliary crane can laterally be attached to the undercarriage of the auxiliary crane via receptacles.
As already explained above, the auxiliary crane advantageously can be connected with the crane via its telescopable boom, wherein the boom tip of the auxiliary crane is directly or indirectly connected with the crane, in particular with the crane uppercarriage and/or the crane ballast receptacle and/or the crane derrick boom.
The boom of the auxiliary crane can be connected with the crane via an interposed connection adapter, wherein the connection adapter preferably is mounted on the pulley head of the auxiliary crane via the bolting points provided for a boom extension.
Between derrick boom and auxiliary crane, variable-length elements in the form of a hydraulic cylinder each, can be provided.
As a suspended ballast, a derrick ballast pallet can be attached. When necessary, further ballast stacks can be attached to the crossbeam, laterally of said pallet.
The crane according to the present disclosure for carrying out the aforementioned method includes a traversable undercarriage, an uppercarriage rotatably mounted on the same with luffing main boom and derrick boom arranged thereon and a crane controller. As derrick ballast, an auxiliary crane and in addition a suspended ballast is provided, which both are connected with a crossbeam via tensioning means which in turn are connected with the derrick boom via guy rods. Between derrick boom and crossbeam, a variable-length element each in the form of a hydraulic cylinder advantageously is provided.
On the undercarriage of the auxiliary crane, receptacles for receiving the slings advantageously are arranged such that they are located closer to the crane than the overall center of gravity of the auxiliary crane. Thereby, the upper chord of the boom constantly is subjected to a tensile load and the lower chord is subjected to a pressure load. Particularly advantageously, the receptacles are designed demountable or each laterally extendable from the undercarriage. In its normal use, the auxiliary crane thus is not limited in its maneuverability by the receptacles. In the auxiliary crane, the receptacles are extended or mounted only during the use as derrick ballast weight.
Further features, details and advantages of the present disclosure will be explained in detail with reference to an exemplary embodiment illustrated in the drawings.